Hi Igor,
The OSG uses OpenGL display lists by default, or
VertexBufferObjects/VertexArrayObjects when enabled via
osg::Geometry::setUserVertexBufferObjects(true) +
setUserVertexArrayObject(true). These GL objects cache the vertex
data within GL, so if you want to update the vertex data you need to
call geometry->dirtyGLObjects() to force the objects to update. You
can also call array->dirty() if you are using VBO/VAO.
If the bounding volume of the geometry changes you'll also want to
force the bounding volume to update by calling Geometry::dirtyBound();
Robert.
On Mon, 2 Jul 2018 at 06:44, Igor Spiridonov <igw...@rambler.ru> wrote:
>
> Hi. I'm wandering if it's ok what i'm doing and how to do it properly.
>
> I have data of primitives which comes from source periodically. These
> primitives are points, lines, polygons. They have different sizes, colors,
> vertices, etc. My first approach was to create a new subscene each time i
> receive new data and replace a current node to a new one. But to create a new
> scene each frame is not very fast operation(a lot of allocation
> /deallocation). So instead of that I've decided to update existing scene by
> changing vertices, primitive types, etc. But I'v noticed that some data
> somewhat cached. For example.
>
>
> Code:
>
> osg::Vec3Array& vertices =
> static_cast<osg::Vec3Array&>(*geometry.getVertexArray());
> vertices.clear();
> for (int i = 0; i < logPolygon.points.size(); i++)
> {
> auto& point = logPolygon.points[i];
> vertices.push_back(osg::Vec3(point.X / 100.f, point.Y / 100.f, 0.f));
> }
>
> geometry.setVertexArray(&vertices); // i need to do that otherwise scene
> is incorrect.
>
>
>
>
> My first question is why do I need to set vertex array again?
> "geometry.setVertexArray(&vertices);"
>
> The second question is it ok to do such update of all properties instead of
> full scene recreation? What other drawbacks can be? Is there a better
> approach?
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=74235#74235
>
>
>
>
>
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